In general, a suspension system of a vehicle is referred to as a suspension and is an apparatus for connecting wheels to a vehicle body, and includes a spring for adjusting transmission of shock from a road surface to a vehicle body, a shock absorber for absorbing shock from the road surface together with the spring, an arm or a link for controlling an operation of the wheel, and a stabilizer for preventing rolling of a vehicle.
The suspension system of the vehicle, which is a significant apparatus for improving ride comfort and driving stability, primarily serves to suppress or rapidly reduce vibration provided from the wheels while stably supporting the vehicle body from the wheels.
A lower arm 1 performing a function of connecting the wheels to the vehicle body and supporting the wheels is used in the suspension system. As illustrated in FIG. 1, the lower arm 1 includes a vehicle body mounting bush 10 (also called “A bush”), a damping joint 20 (also called “G bush”), and a ball joint 30 at respective ends thereof, so that the wheels are mounted in the vehicle body.
Here, the vehicle body mounting bush 10 and the damping joint 20 are connected and coupled to a vehicle body frame 2 by assembling bolts 41 and 42, respectively, and the ball joint 30 is coupled with a knuckle of the wheel to support the wheels together with an upper arm.
In the meantime, as illustrated in FIG. 2, the damping joint 20 includes an interior pipe member 21 having a predetermined diameter, a buffer member 22 made of rubber and having both side center portions perforated by the interior pipe member 21 to be installed so as to surround an external circumferential surface of the interior pipe member 21, and an exterior pipe member 23 coupled while surrounding the external circumferential surface of the buffer member 22.
The damping joint 20 including the aforementioned configuration simultaneously prevents an impact harshness phenomenon that is single vibration generated followed by shock sound when tires of a driving vehicle pass through a projection of road surface, a shimmy phenomenon that is horizontal shakiness in a direction in which a steering wheel of a turning vehicle is rotated, and a judder phenomenon, in which noise or vibration is generated in the steering wheel or a dash panel when braking force is generated when the vehicle is driven at a high speed, among random excitation transmitted from the outside of the vehicle.
Further, the damping joint 20 supports all loads transmitted to the lower arm 1. In order to effectively support the load of the vehicle, a plurality of holes in a direction of the load is formed in the buffer member 22 included in the damping joint 20 or a separate reinforcing steel or a reinforcing member made of plastic or urethane is integrally inserted inside the buffer member 22.
However, if a plurality of reinforcing members is applied in order to support the load of the vehicle, general durability of the damping joint 20 deteriorates and the damping joint 20 is easily aged when the reinforcing member is made of rubber, thereby causing frequent damage.